Sonic30ss

Blew up a B III X this weekend- like really blew it up, stripped bottom gears, snapped vert shaft, pushed upper gears out the to to the point where the top cap is gone- was running at peak torque right at 4100 rpm. I'm going to toss another on the boat and hopefully make the rest of the season. Planning on replacing both in the spring and looking for some input to help to make the right decision.

The boat- 45 Wellcraft Excalibur about 21,000 lbs with 540's 640hp@5200-690 ft/lbs@4100 rpm. running 28 pitch 3x3 prop set.
Spend most of the time cruising at 40-44 mph right at 4100, the hull seems to be happy there.

Do you think B III XR will hold up?
Thinking about a Bravo "type" drive Teague or IMCO with single prop if it will work with this hull.

Thanks

Griff

Bravo3 no matter what kind won't hold up with that weight and torque.

I'd go with B Max drives and 5 blade props

Knot 4 Me

I don't see the III XR holding up any better than the III X. Agree with Griff that you probably need to look for a beefy Bravo I style drive (B Max, SCX) and play with props. Or Arnesons!

253

I would call,, Max Machine,, in Arizona to see what they recommend, those guys are among the best in the business for 19 years now.

Sonic30ss

So I threw a new X drive on to get thru the rest of the season...there is a huge physical difference between the old and new drive. It looks like there is more material added to both the upper and lower and the finned top cap is definitely beefier.
My water pressure is better with the pickups in the bullet too.
Internally what is the difference between the old non swept back and the new swept back drive?

253

BravoX has a Steel lower tower, Thick Ribbed upper cap, Thick Floor Gears,,Bravo1 has Aluminum towers, thinner top cap, 1999 & older have thin floor gears.,

zemaestro

Yes they are heavy boats. I was told that the bravo 3 lower is actually pretty stout. The 47 that used to have built 496 mags with whipples made a little more power than you had bravo 3 xr's (uppers were worked over) that held up pretty well. Max machine towers with xr gears, dual showers, amsoil marine mixed wit lucas. 28's got him low 60's. On your boat 28's seem a little steep, would under propping help at all? They were not happy,but they survived....

Sonic30ss

Thanks I spoke to Matt about his set up.
I'll prob go with worked XR uppers and cryo lowers, I'm using the "special mix" oil now and drives seem to be happy (for now)
I tried 26's last season boat handeled awful, bow steering, more rpms with lower speeds throughout entire rpm range.
Haven't done a real full throttle run yet this year but mid range is up 3-4 mph at same rpms 4000-4100

zemaestro

Here I go....its a risk. But have you ever considered a bravo 2 lower. I have been doing much reading and although they are not designed for speed it seems as thought they are tougher than the Bravo 3 lower. I admit I had never really looked at them before. These are not raceboats, were never meant to be, and never will be....I too am only concerned about my cruise speed. The boat simply is not happy at 33 mph. They really needed to be shipped from the factory with a 10.2 deck BBC with a decent stroke. I also hope that a yet to be designed (affordable) drive is in our future. I am so sick of mercruiser junk, it is sub-par and just not acceptable after all these years.

Sonic30ss

I have considered a B2, my concern was if it had enough blade area to work with such a heavy boat, when I talked to 47Excal he confirmed blade area concerns. I don't want to experiment and potentially waste $$ on drives and props.
You are absolutely correct about 33 mph, last year (first season with boat) I was running my cruise speed at 35 and the boat felt heavy and sluggish, push throttles up to get to 40 and it was a completely different animal, light (ha!), responsive, ride quality and handeling was 100% better.
Yes they are def not race boats but do require big torque to move at 40 mph. Riviera didn't have much choice in engine/drive packages, I guess they took what they could get, adding blower engines and 6's would have pushed price thru stratosphere
In all fairness to Merc we are pushing these drives beyond their design parameters, 21,000# and 690 ft/lbs in my case. IMO choices are #6, Arneson or modify B III XR uppers, cryo lowers and check at end of every season. It looks like Merc has really beefed the uppers when comparing my old X to new X.
I don't think it's possible to build an "affordable" drive to do what we are asking them to do.